WO2021240999A1

WO2021240999A1 - Exhaust gas purification catalyst device

Info

Publication number: WO2021240999A1
Application number: PCT/JP2021/014375
Authority: WO
Inventors: 琢斗荒川; 祐也河野; 翼南條; 嘉典山下
Original assignee: 株式会社キャタラー
Priority date: 2020-05-26
Filing date: 2021-04-02
Publication date: 2021-12-02
Also published as: US20230149907A1; JP2021186704A; BR112022018717A2; JP6994079B2

Abstract

This exhaust gas purification catalyst device comprises: a substrate; and one or more catalyst layers on the substrate. Among the one or more catalyst layers, at least one catalyst layer contains both Cu-CHA-type zeolite particles and iron-supporting metal oxide particles in which iron is supported on metal oxide particles.

Description

Exhaust gas purification catalyst device

The present invention relates to an exhaust gas purification catalyst device.

A selective catalytic reduction (SCR) system is known as a technique for reducing and purifying NOx in exhaust gas discharged from an internal combustion engine such as a diesel engine before it is released to the atmosphere. The SCR system is a technique using an SCR catalyst that reduces _{NO x} in exhaust gas to N ₂ by using a reducing agent such as ammonia.

However, in this technique, it occurs dinitrogen monoxide (N 2 _O) formation reaction, the resulting N _{2 O} is to be discharged from the SCR system. This N ₂ O formation is thought to occur as a side reaction in the process of reducing _{NOx to N 2} by the SCR reaction or in the process of ammonia acting as a reducing agent.

By the way, regulations on exhaust gas from internal combustion engines are being tightened year by year, and in recent years, the "GHG regulations" that regulate greenhouse gases (greenhouse gases) have been significantly tightened.

Since N ₂ O contributes greatly as a greenhouse gas, it is desired that the amount _{of N 2 O emitted from the internal combustion engine is as small as possible.}

In this regard, Patent Document 1 describes a first catalyst composition layer containing a mixed oxide (eg, vanasia / titania) and a second catalyst composition layer containing a metal exchanged zeolite (eg, Cu-zeolite). but on a substrate, which is disposed from the upstream side of the exhaust gas flows in this order, describes a SCR catalyst system, emissions of N _{2 O} is described as be reduced by this configuration.

Special Table 2016-518244

An object of the present invention, emissions of N 2 _{_O} (N 2 _O slip amount) is extremely suppressed, it is to provide an exhaust gas purifying catalyst device.

The present invention is as follows.

<< Aspect 1 >> An exhaust gas purification catalyst device including a base material and one or a plurality of catalyst layers on the base material.
At least one catalyst layer among the one or a plurality of catalyst layers is
It contains both Cu-CHA-type zeolite particles and iron-supported metal oxide particles in which iron is supported on the metal oxide particles.
Exhaust gas purification catalyst device.
<< Aspect 2 >> The metal oxide particles are one type of metal oxide particles selected from the group consisting of alumina, silica, titania, zirconia, and ceria, or two or more types of metal composite oxide particles. The exhaust gas purification catalyst device according to the first aspect.
<< Aspect 3 >> The exhaust gas purification catalyst device according to Aspect 2, wherein the metal oxide particles are alumina particles.
<< Aspect 4 >> The amount of iron in the exhaust gas purification catalyst device is 0.3 g / L or more and 1.3 g / L or less as the mass of iron in terms of ferric _{oxide (Fe 2} O _{3) per 1 L of the base material.} The exhaust gas purification catalyst device according to any one of aspects 1 to 3.
<< Aspect 5 >> The amount of iron in the exhaust gas purification catalyst device is 0.6 g / L or more and 1.3 g / L or less as the mass of iron in terms of ferric _{oxide (Fe 2} O _{3) per 1 L of the base material.} The exhaust gas purification catalyst device according to any one of aspects 1 to 3.
<< Aspect 6 >> The ratio of the Cu-CHA type zeolite particles and the iron-supported metal oxide particles in the catalyst layer is 5% by mass or more as the mass percentage of the iron-supporting metal oxide particles to the total of both. The exhaust gas purification catalyst device according to any one of aspects 1 to 5, wherein the mass is not more than%.
<< Aspect 7 >> The exhaust gas purification catalyst device according to any one of aspects 1 to 6, which is for selective contact reduction.
<< Aspect 8 >> The method for manufacturing an exhaust gas purification catalyst device according to any one of aspects 1 to 7.
(1) The Cu-CHA type zeolite particles and the iron-supported metal oxide particles are mixed and wet-ground to obtain a slurry for forming a catalyst layer, and (2) the catalyst is placed on the substrate. A layer-forming slurry is applied and fired to form the catalyst layer on the substrate.
Manufacturing method of exhaust gas purification catalyst device.
<< Aspect 9 >> An exhaust gas purification method for purifying exhaust gas using the exhaust gas purification catalyst device according to Aspect 7.
The exhaust gas purification catalyst device is supplied with an exhaust gas and a reducing agent to reduce NO _x in the _{exhaust gas to N 2} .
Exhaust gas purification method.

According to the present invention, emissions of N 2 _{_O} (N 2 _O slip amount) is extremely suppressed, the exhaust gas purifying catalyst device is provided.

FIG. 1 is an XRD chart of the spray-dried iron alumina used in Example 3 (2θ = 10 to 80 °). FIG. 2 is an XRD chart of the spray-dried iron alumina used in Example 3 (2θ = 29 to 35 °). FIG. 3 is an XRD chart of the spray-dried iron alumina used in Example 3 (2θ = 48 to 54 °). FIG. 4 is an XRD chart of the impregnated iron alumina used in Example 5 (2θ = 10 to 80 °). FIG. 5 is an XRD chart of the impregnated iron alumina used in Example 5 (2θ = 29 to 35 °). FIG. 6 is an XRD chart of the impregnated iron alumina used in Example 5 (2θ = 48 to 54 °).

The exhaust gas purification catalyst device of the present invention
An exhaust gas purification catalyst device including a base material and one or more catalyst layers on the base material.
At least one of the above one or a plurality of catalyst layers is
It is characterized by containing both Cu-CHA type zeolite particles and iron-supported metal oxide particles in which iron is supported on the metal oxide particles.

The technique of Patent Document 1 _{focuses on the difference in N 2} producing ability and N ₂ O producing ability between the mixed oxide and the metal exchange zeolite, and focuses on the function of the mixed oxide and the metal exchange zeolite. It is intended to be used separately from the functions. Then, _{the first catalyst composition layer containing the mixed oxide, which has an excellent N 2} forming ability and a _{low N 2} O forming ability, is first brought into contact with the NOx-rich exhaust gas to suppress the formation of _{N 2 O.} It is based on the idea that.

However, the present inventors have found that the N 2 _O slip amount of inhibition were considered as follows.

N ₂ O, for example, derived from the degradation reaction of ammonium nitrate which is an intermediate of the SCR reaction _(NH 4 · NO _3). Generation of N _{2 O} by the decomposition of ammonium nitrate is believed to be facilitated by metal-exchanged zeolite (e.g. Cu- zeolites). On the other hand, mixed oxides (e.g. iron-based material) is believed to promote the decomposition of the generated N _{2 O.}

Therefore, if the metal exchange zeolite and the mixed oxide are arranged close to each other, it _{is expected that N 2} O generated by the action of the metal exchange zeolite is immediately decomposed, and as a result, the _{amount of N 2} O slip can be suppressed.

In this regard, in the SCR catalyst system described in Patent Document 1, the metal exchange zeolite and the mixed oxide are arranged in separate layers. Then, the degree of proximity between the two is reduced. Therefore, in the SCR catalyst having such a structure, not in contact generated N _{2 O} is a mixed oxide, thus believed that it is discharged without being decomposed.

In the present invention, based on the above considerations, Cu-CHA-type zeolite particles and iron-supported metal oxide particles are arranged in the same catalyst layer to increase the degree of proximity between the two, thereby N ₂ We have reached an exhaust gas purification catalyst device in which the amount of O-slip is sufficiently suppressed. The present invention is not bound by any particular theory.

Hereinafter, the components of the exhaust gas purification catalyst device of the present invention will be described in detail in order.

"Base material"
As the base material in the exhaust gas purification catalyst device of the present invention, those generally used as the base material of the exhaust gas purification catalyst device can be used. For example, it may be, for example, a straight flow type monolith honeycomb base material composed of materials such as cordierite, SiC, stainless steel, and inorganic oxide particles.

《Catalyst layer》
The exhaust gas purification catalyst device of the present invention has one or a plurality of catalyst layers, one of which contains both Cu-CHA-type zeolite particles and iron-supported metal oxide particles. That is, in the exhaust gas purification catalyst device of the present invention, the Cu-CHA type zeolite particles and the iron-supported metal oxide particles are contained in the same catalyst layer.

Hereinafter, in the present specification, a catalyst layer containing both Cu-CHA type zeolite particles and iron-supported metal oxide particles is referred to as a "specific catalyst layer".

<Cu-CHA type zeolite particles>
The Cu-CHA-type zeolite particles in the present invention mean particles composed of CHA (Chabazite) -type zeolite ion-exchanged with copper. As the Cu-CHA type zeolite particles, those known as SCR catalysts may be appropriately selected and used.

Cu-CHA-type zeolite particles, from the viewpoint of ensuring high SCR catalytic _{ability, SAR (Silica Alumina Ratio, SiO} 2 / Al 2 O 3 molar ratio), 20 or less, 18 or less, 15 or less, 12 or less, 10 or less , 9 or less, or 8 or less.

On the other hand, if the SAR of the Cu-CHA type zeolite is excessively low, the specific surface area of the zeolite may become small and the NO _x purification ability may be impaired. From the viewpoint of avoiding this, the SAR of the Cu-CHA type zeolite particles may be 3 or more, 4 or more, 5 or more, 6 or more, or 7 or more.

It is believed that Cu in the Cu-CHA-type zeolite particles is supported on the surface Al site of the CHA-type zeolite and constitutes a catalytic activity point for _{NO x purification in the SCR catalyst.} The amount of Cu in the Cu-CHA type zeolite is 0.05 or more, 0.10 or more, 0.15 or more, from the viewpoint of expressing _{high NO x} purification ability as the molar ratio (Cu / Al) of Cu and Al. It may be 0.20 or more or 0.25 or more, and _{from the viewpoint of stably maintaining the NO x} purification ability, 1.00 or less, 0.80 or less, 0.60 or less, 0.50 or less, 0. It may be 45 or less, 0.40 or less, 0.35 or less, 0.30 or less, or 0.25 or less.

The Cu-CHA type zeolite particles in the present invention may contain an alkali metal. Cu-CHA-type zeolite containing an appropriate amount of alkali metal further improves its hydrothermal durability while maintaining high initial NOx purification ability. On the other hand, if the amount of alkali metal contained in the Cu-CHA type zeolite particles is excessively large, the initial NO _x purification ability may be impaired.

From these viewpoints, the amount of alkali metal in the Cu-CHA type zeolite particles is _{0.2 mass as the ratio of the M 2} O (M indicates an alkali metal) equivalent mass to the total mass of the Cu-CHA type zeolite. % Or more, 0.3% by mass or more, 0.4% by mass or more, 0.5% by mass or more, 0.6% by mass or more, 0.7% by mass or more, or 0.8% by mass or more. 2.0% by mass or less, 1.8% by mass or less, 1.6% by mass or less, 1.4% by mass or less, 1.2% by mass or less, 1.0% by mass or less, 0.9% by mass or less, or It may be 0.8% by mass or less.

The alkali metal contained in the Cu-CHA type zeolite particles may be lithium (Li), sodium (Na), potassium (K), cesium (Cs) or the like, and may be typically potassium.

The primary particle size of the Cu-CHA type zeolite particles may be 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, or 0.4 μm or more, and may be 1.0 μm or less, 0.8 μm or less, 0.6 μm. Hereinafter, it may be 0.5 μm or less, or 0.4 μm or less.

The amount of Cu-CHA-type zeolite particles in the exhaust gas purification catalyst device of the present invention is 70 g / L or more, 80 g, from the viewpoint of ensuring a sufficiently high SCR catalytic ability as the mass of Cu-CHA-type zeolite per 1 L of the base material. It may be / L or more, 100 g / L or more, 120 g / L or more, 130 g / L or more, or 140 g / L or more, and from the viewpoint of suppressing pressure loss of the exhaust gas purification catalyst device, 200 g / L or less, 180 g / L or less. , 160 g / L or less, 150 g / L or less, or 140 g / L or less.

<Iron-supported metal oxide particles>
The iron-supported metal oxide particles in the present invention are particles in which iron is supported on the metal oxide particles.

The metal oxide particles may be oxide particles of one kind of metal selected from alumina, silica, titania, zirconia, ceria and the like, or composite oxide particles of two or more kinds of metals. The metal oxide particles are typically alumina particles.

The iron-supported amount of the iron-supported metal oxide particles is converted to _{ferric oxide (Fe 2} O ₃ ) with respect to the total mass of the iron-supported metal oxide particles from the viewpoint of sufficiently suppressing _{the N 2 O slip amount.} The proportion of iron in the mass may be 0.5% by mass or more, 1% by mass or more, 3% by mass or more, 5% by mass or more, 6% by mass or more, or 7% by mass or more. On the other hand, the supported amount of iron, 20 wt% or less, 15 wt% or less, 12 wt% or less, or even 10 wt% or less, sufficiently high _{N 2} O slip suppression effect is obtained.

The iron (for example, ferric oxide) in the iron-supported metal oxide particles may be in the form of particles and may have a particle size of about 1 nm or more and 50 nm or less.

Such iron-supported metal oxide particles may be prepared by, for example, an appropriate method such as a spray-drying method or an impregnation method using desired metal oxide particles.

The production of iron-supported metal oxide particles by the spray-drying method may be carried out, for example, by a method including the following steps:
The sol of the desired metal oxide particles and the iron compound are mixed in a suitable solvent (eg, water) to prepare a mixed solution;
The resulting mixture is spray-dried to give a dry powdered precursor particle gel; and the resulting precursor particle gel is calcined.

The production of iron-supported metal oxide particles by the impregnation method may be carried out, for example, by a method including the following steps:
Immersing the desired metal oxide particles in a solution of the iron compound in a suitable solvent (eg, water); and firing the soaked metal oxide particles.

The iron compound used in the spray-drying method and the impregnation method may be a solvent-soluble iron compound or a water-soluble iron compound, and specifically, for example, iron sulfate, iron nitrate, iron chloride, etc. It may be potassium hexacyanoferrate or the like.

The primary particle size of the iron-supported metal oxide particles may be 0.01 μm or more, 0.03 μm or more, or 0.05 μm or more, and may be 1 μm or less, 0.5 μm or less, or 0.2 μm or less.

In the iron-supported metal oxide particles, it is desirable that the iron supported on the metal oxide particles is dispersed as high as possible. Specifically, in the XRD measured for the pulverized product of the iron-supported metal oxide particles, the _{crystal peaks attributed to ferric oxide (Fe 2} O ₃ ) may be highly dispersed so as not to be observed. In the XRD measurement, the crystal peak of ferric oxide is observed around 2θ = 31 ° and 51 °.

The amount of the iron supported metal oxide particles in the exhaust gas purifying catalyst device of the present invention, as the mass of the iron-supported metal oxide per substrate 1L, from the viewpoint of sufficiently high effect of suppressing N 2 _O slip amount, 1 g / It may be L or more, 3 g / L or more, 5 g / L or more, 10 g / L or more, or 12 g / L or more, and from the viewpoint of suppressing pressure loss of the exhaust gas purification catalyst device, 30 g / L or less, 25 g / L or less, It may be 20 g / L or less, 18 g / L or less, or 15 g / L or less.

From the same viewpoint, the amount of iron in the exhaust gas purification catalyst device is 0.3 g / L or more and 0.5 g / L as the mass of iron in terms of ferric _{oxide (Fe 2} O _{3) per 1 L of the base material.} It may be 1.7 g / L or more, or 1.0 g / L or more, and 1.3 g / L or less, 1.2 g / L or less, 1.1 g / L or less, or 1.0 g / L or less. It may be there.

<Ratio of Cu-CHA type zeolite particles and iron-supported metal oxide particles>
In the exhaust gas purifying catalyst device of the present invention, in particular the catalyst layer, and the Cu-CHA-type zeolite particles, the ratio of the iron supported metal oxide particles, and the SCR catalytic activity, the balance between the suppression effect of N 2 _O slippage From the viewpoint, the mass ratio (mass percentage) of the iron-supported metal oxide to the total mass of the Cu-CHA type zeolite and the iron-supported metal oxide is 5% by mass or more, 7% by mass or more, 10% by mass or more, and 12% by mass. It may be more than or equal to 15% by mass, and may be 20% by mass or less, 18% by mass or less, 15% by mass or less, or 12% by mass or less.

<Arbitrary component of specific catalyst layer>
The specific catalyst layer in the exhaust gas purification catalyst device of the present invention contains both Cu-CHA type zeolite particles and iron-supported metal oxide particles. In addition to these, the specific catalyst layer may contain other optional components.

The other component contained in the specific catalyst layer may be, for example, metal oxide particles other than Cu-CHA type zeolite particles and iron-supported metal oxide particles, a binder and the like.

The other metal oxide particles may be, for example, oxide particles of one kind of metal selected from alumina, silica, titania, zirconia, ceria and the like, or composite oxide particles of two or more kinds of metals. The binder may be, for example, a calcined product of a metal oxide sol such as an alumina sol, a silica sol, a titania sol, or a zirconia sol.

<Amount of specific catalyst layer>
The amount (coating amount) of the specific catalyst layer in the exhaust gas purification catalyst device of the present invention is 80 g / L or more and 100 g / L from the viewpoint of exhibiting a sufficiently high SCR catalytic ability as the mass of the specific catalyst layer per 1 L of the base material. It may be L or more, 120 g / L or more, 130 g / L or more, or 140 g / L or more, and from the viewpoint of suppressing pressure loss of the exhaust gas purification catalyst device, 250 g / L or less, 200 g / L or less, 180 g / L or less, It may be 160 g / L or less, 150 g / L or less, or 140 g / L or less.

<Other catalyst layers>
The exhaust gas purification catalyst device of the present invention has a specific catalyst layer. The exhaust gas purification catalyst device of the present invention may have other catalyst layers in addition to the specific catalyst layer, if necessary.

The other catalyst layer in the exhaust gas purification catalyst device of the present invention may be, for example, a catalyst layer exhibiting NOx oxidizing ability, a catalyst layer exhibiting ASC (Ammonia Slip Catalyst, ammonia slip catalyst) ability, or the like. These may have the same structure as the known catalyst layer. Further, in the exhaust gas purification catalyst device of the present invention, the specific catalyst layer and the other catalyst layers may be laminated on the base material in any order, or the exhaust gas may be present on the base material in any order. It may exist as a catalyst layer on the upstream side and the downstream side in the flow direction.

<< Manufacturing method of exhaust gas purification catalyst device >>
The exhaust gas purification catalyst device of the present invention may be manufactured by any method as long as it has the above configuration. As an example of the exhaust gas purification catalyst device of the present invention, a case where a characteristic catalyst layer is provided as a single layer on a base material is taken as an example, and the following method is exemplified as a manufacturing method thereof:
(1) Cu-CHA type zeolite particles and iron-supported metal oxide particles are mixed and wet-ground to obtain a catalyst layer forming slurry (catalyst layer forming slurry preparation step), and (2) group. A catalyst layer forming slurry is applied on a material and fired to form a catalyst layer on a substrate (catalyst layer forming step).
A method for manufacturing an exhaust gas purification catalyst device, including.

In the catalyst layer forming slurry preparation step, the Cu-CHA type zeolite particles specified in the present invention and the iron-supported metal oxide particles specified in the present invention are mixed at a predetermined ratio and wet-ground, and the catalyst layer forming slurry is pulverized. (Slurry for forming a specific catalyst layer) is obtained.

The pulverization in this slurry preparation step for forming a catalyst layer is suitable from the viewpoint of making the particle size of each particle uniform and stabilizing the catalytic activity, and particularly from the viewpoint of suppressing the generation of crystal defects of Cu-CHA type zeolite particles. It is carried out by wet grinding performed in a liquid medium (for example, water).

Wet pulverization may be performed using an appropriate pulverizer such as a ball mill, a bead mill, a jet mill, or an air jet mill, using an appropriate liquid medium, for example.

In the catalyst layer forming step, the catalyst layer forming slurry is applied onto the base material and fired to form the catalyst layer on the base material.

The base material may be appropriately selected depending on the base material in the desired exhaust gas purification catalyst device, and may be, for example, a straight flow type monolith honeycomb base material manufactured by Cordellite.

The slurry for forming a catalyst layer on the substrate may be applied and fired by a known method, respectively, or by a method obtained by appropriately modifying a known method by a person skilled in the art. The firing temperature may be, for example, 300 ° C. or higher, 350 ° C. or higher, 400 ° C. or higher, 450 ° C. or higher, or 500 ° C. or higher, and may be, for example, 1,000 ° C. or lower, 800 ° C. or lower, 700 ° C. or lower, 600 ° C. or higher. It may be ℃ or less, 550 ℃ or less, or 500 ℃ or less.

<< Applications of exhaust gas purification catalyst equipment >>
The exhaust gas purification catalyst device of the present invention may be used as a catalyst device for selective catalytic reduction (SCR) for purifying exhaust gas discharged from, for example, a diesel internal combustion engine, a gasoline internal combustion engine, or the like.

The exhaust gas purification catalyst device of the present invention also includes a DPF (Diesel Particulat Filter) device, a GPF (Gasoline Particulat Filter) device, and an ASC (Ammonia Slip Catalyst) device. May be used as part of an exhaust gas purification catalyst system in combination with one or more selected from the above.

<< Exhaust gas purification method >>
The present invention further provides an exhaust gas purification method for purifying exhaust gas using the exhaust gas purification catalyst device of the present invention.

The exhaust gas purification method of the present invention is a method including supplying an exhaust gas and a reducing agent to the exhaust gas purification catalyst device of the present invention to reduce _{NO x} in the _{exhaust gas to N 2.}

The reducing agent in the exhaust gas purification method of the present invention may be, for example, ammonia, aqueous ammonia, urea, hydrocarbons, atomized fuel or the like. The exhaust gas purifying catalyst device of the present invention, derived from ammonia (NH ₃₎ used as a reducing agent in the SCR reaction, since N 2 _O generated is what is extremely suppressed, as the reducing agent, in particular, ammonia, ammonia One or more selected from water and urea may be used.

In the following examples, a honeycomb base material made of cordierite having a cell density of 400 cpsi (cell per square inch, wall thickness of 6 mil (0.15 mm), and a capacity of 35 mL) was used as the base material.

As the Cu-CHA type zeolite particles, particles having a silica / alumina molar ratio (SAR) of 7.5 and a molar ratio of Cu to Al (Cu / Al) of 0.25 were used.

<< Example 1 >>
(1) Preparation of slurry for forming a catalyst layer In 200 parts by mass of pure water, 100 parts by mass of silica binder sol dispersion (15 parts by mass of dry mass), 85 parts by mass of Cu-CHA type zeolite particles, and iron-supported metal oxide. as particles, iron-alumina particles (spray drying iron alumina particles, Fe ₂ O ₃ supported amount 9.0 wt%) 2 parts by weight, were mixed in this order, by milling by a wet grinding method, a catalyst layer formed Slurry was obtained.

(2) Manufacture of Exhaust Gas Purification Catalyst Device The catalyst layer forming slurry obtained above is applied onto a substrate so that the coating amount after firing is 142.8 g / L, dried at 250 ° C., and then dried. By firing at 500 ° C. for 1 hour, a catalyst layer was formed on the substrate to manufacture an exhaust gas purification catalyst device. The coating amount of the additive (iron alumina particles) in the catalyst layer of this external gas purification catalyst device was 2.8 g / L. Next, this exhaust gas purification catalyst device was subjected to evaluation of SCR performance after being endured at 630 ° C. for 50 hours in a hydrothermal endurance furnace.

(3) Evaluation of SCR performance The evaluation of the SCR performance of the exhaust gas purification catalyst device obtained above was performed using a model gas.

First, the exhaust gas purification catalyst device is heated to raise the temperature from room temperature to 600 ° C. at a heating rate of 25 ° C./min, and the gas having the composition of gas condition 1 shown in Table 1 below is inserted into the exhaust gas purification catalyst device. Was circulated at a space velocity (SV) of 60,000 h- ^1. Immediately after the temperature of the device reached 600 ° C., the heating was stopped and the device was allowed to cool. After the device temperature drops to 500 ° C., while maintaining this temperature, the gas having the composition of gas condition 2 shown in Table 2 below is ^{circulated at a space velocity (SV) of 60,000 h -1} to exhaust gas. The composition of NO _x was examined, and the purification rate of _{NO x and the amount of N 2} O slip were calculated. The results are shown in Table 3.

<< Examples 2 to 4 and Comparative Examples 1 and 2 >>
Spray-drying method Slurries for forming a catalyst layer were prepared in the same manner as in Example 1 except that the amount _{of Fe 2} O _{3 supported on the iron alumina particles was changed as shown in Table 3.} Using this, the slurry for forming a catalyst layer was applied onto the substrate in the same manner as in Example 1 except that the coating amount was changed so that the coating amount after firing was the value shown in Table 3. , Drying and firing were performed to manufacture an exhaust gas purification catalyst device.

In Comparative Example 2, the amount of pure water used when preparing the slurry for forming the catalyst layer was set to 250 parts by mass.

The durability and SCR performance of the obtained exhaust gas purification catalyst device were evaluated in the same manner as in Example 1. The results are shown in Table 3.

<< Example 5 >>
Exhaust gas purification is carried out in the same manner as in Example 3 except that the impregnated iron alumina particles _{having the same amount of Fe 2} O ₃ supported on the alumina by the impregnation method are used instead of the spray dry iron alumina particles. The catalyst device was manufactured and evaluated. The results are shown in Table 3.

<< Comparative Example 3 >>
Spray-dry method An exhaust gas purification catalyst device was manufactured and evaluated in the same manner as in Example 3 except that a mixture of 9.1 parts by mass of alumina and 0.9 parts by mass of iron oxide was used instead of the iron alumina particles. bottom. The results are shown in Table 3.

In the evaluation of the exhaust gas purifying catalyst device of the present invention, the value of the NOx purification rate has good larger, the value of N 2 _O slip amount is smaller is better.

Referring to Table 3, compared with Comparative Example 1 containing no iron-supported metal oxide particles, in Examples 1 to 4 containing iron supported metal oxide particles are N 2 _O slip amount is suppressed, further, according proportion of iron supported metal oxide particles coated layer is increased, N 2 _O slip amount tended to decreases. However, the proportion of iron supported metal oxide particles coated layer is more than 2.0 mass%, in the above about 4.8 wt%, decreasing the N 2 _O slip amount becomes moderate.

From these, the proportion of iron supported metal oxide particles coated layer is from the viewpoint of suppressing _{N 2} O slip amount, 2.0 mass% or more, 3.0 wt% or more, 4.0 wt% The above or 4.5% by mass or more may be used, and from the viewpoint of the effectiveness of the formulation, it may be 20% by mass or less, 18% by mass or less, or 16% by mass or less.

Further, the amount of iron in the exhaust gas purification catalyst device ( _{the mass of iron in terms of ferric oxide (Fe 2} O ₃ ) per 1 L of the base material) is in the range of 0.3 g / L or more and 2.5 g / L or less. if, in comparison with Comparative example, which is N 2 _O slip amount is suppressed and good results were obtained. Further, when the amount of iron in the exhaust gas purification catalyst device was in the range of 0.6 g / L or more and 2.5 g / L or less, the NOx purification ability was also excellent as compared with the comparative example.

In Comparative Example 2 not including Cu-CHA-type zeolite, since the catalyst layer has no NOx resolution, _{N 2} O slip amount became apparent 0.00. Further, in the catalyst device of Comparative Example 2, _{the oxidation reaction of NH 3} occurred, and therefore, the NOx purification rate showed a negative value in calculation.

<< Examples 6 and 7 >>
Exhaust gas purification catalysts were prepared in the same manner as in Example ₃ _{except that the amount of Fe 2} O 3 supported on the iron alumina particles was changed as shown in Table 4. Manufactured the device.

The durability and SCR performance of the obtained exhaust gas purification catalyst device were evaluated in the same manner as in Example 1. The results are shown in Table 4 together with the evaluation results of Comparative Example 1 and Example 3.

_{Referring to Table 4, the amount of N 2} O slip is suppressed in Examples 3, 6 and 7 containing iron-supported metal oxide particles as compared with Comparative Example 1 containing no iron-supported metal oxide particles. _{Furthermore, as the Fe 2} O ₃ carrying ratio in the iron-supported metal oxide particles increased, the N ₂ O slip amount tended to decrease. _{From this, if the Fe 2} O ₃ supporting ratio in the iron-supported metal oxide particles in the coat layer is 2.0% by mass or more, the effect of suppressing the amount of _{N 2 O slip can be exhibited.} 2.0 mass% or more, 4.0 wt% or more, or if 5.0 mass% or more, the effect of suppressing the N 2 _O slip amount is preferably expressed was confirmed.

<< Examples 8 to 11 >>
The catalyst layer was formed in the same manner as in Example 3 _{except that the iron-supported metal oxide particles (Fe 2} O ₃ supported amount 9.0% by mass) shown in Table 5 were used instead of the iron alumina particles. A slurry for exhaust gas was prepared and used to manufacture an exhaust gas purification catalyst device.

The durability and SCR performance of the obtained exhaust gas purification catalyst device were evaluated in the same manner as in Example 1. The results are shown in Table 5 together with the evaluation results of Comparative Example 1 and Example 3.

The abbreviations in the iron-supported metal oxide particle column in Table 5 have the following meanings.
Spray-dry method Iron alumina: _{Particles in which iron oxide (Fe 2} O ₃ ) is carried on γ-alumina, manufactured by the spray-dry method Spray-dry method Iron silica alumina: Silica alumina (SiO ₂ : Al ₂ O ₃ = 5: 5: 95 (mass ratio)) on which iron oxide (Fe ₂ O ₃ ) is carried, manufactured by the spray dry method Spray dry method Iron thiania: particles on which iron oxide (Fe ₂ O ₃ ) is carried on titania, Manufactured by the spray-dry method Spray-dry method Iron ceria: _{Particles in which iron oxide (Fe 2} O ₃ ) is supported on ceria, manufactured by the spray-dry method

From the results in Table 5, it was confirmed that the effects of the present invention are exhibited even when silica alumina, titania, ceria or the like is used as the carrier in the iron-supported metal oxide particles in addition to alumina.

<< Comparative Example 4 >>
(1) Preparation of Slurry 1 for Forming Catalyst Layer In 250 parts by mass of pure water, 5 parts by mass of alumina binder sol and iron alumina as iron-supported metal oxide particles (Fe ₂ O ₃ content 9.0% by mass). 95 parts by mass of the particles were mixed in this order and pulverized by a wet pulverization method to obtain a catalyst layer forming slurry 1.

(2) Preparation of Slurry 2 for Forming Catalyst Layer In 200 parts by mass of pure water, 100 parts by mass of silica binder sol dispersion (15 parts by mass of dry mass) and 85 parts by mass of Cu-CHA type zeolite particles are mixed in this order. Then, the slurry 2 for forming a catalyst layer was obtained by pulverizing by a wet pulverization method.

(3) Manufacture of Exhaust Gas Purification Catalyst Device A slurry 1 for forming a catalyst layer was applied onto a substrate so that the coating amount after firing was 14 g / L, and dried at 250 ° C. Next, the catalyst layer forming slurry 1 is applied onto the substrate after coating and drying so that the coating amount after firing is 140 g / L, and the catalyst layer forming slurry 2 is dried at 250 ° C. and then dried. By firing at 500 ° C. for 1 hour, a catalyst layer composed of a lower layer containing iron-supported metal oxide particles and an upper layer containing Cu-CHA-type zeolite particles is formed on the substrate to form an exhaust gas purification catalyst device. Manufactured.

(4) Evaluation of SCR performance The SCR performance of the exhaust gas purification catalyst device obtained above was evaluated in the same manner as in Example 1. The results are shown in Table 6.

<< Comparative Example 5 >>
Using the catalyst layer forming slurry 1 and the catalyst layer forming slurry 2 prepared in the same manner as in Comparative Example 4, Cu was placed on the substrate in the same manner as in Comparative Example 3 except that the order of application was reversed. An exhaust gas purification catalyst device was manufactured by forming a catalyst layer composed of a lower layer containing CHA-type zeolite particles (coating amount 140 g / L) and an upper layer containing iron-supported metal oxide particles (coating amount 14 g / L). The SCR performance of the obtained exhaust gas purification catalyst device was evaluated in the same manner as in Example 1. The results are shown in Table 6.

<< Comparative Example 6 >>
An exhaust gas purification catalyst device obtained in the same manner as in Comparative Example 1 is placed on the upstream side of the exhaust gas flow.
An exhaust gas purification catalyst device obtained in the same manner as in Comparative Example 2 is placed on the downstream side of the exhaust gas flow.
They were arranged and connected in series to form a tandem type exhaust gas purification catalyst system. The SCR performance of the obtained exhaust gas purification catalyst system was evaluated in the same manner as in Example 1. The results are shown in Table 6.

<< Comparative Example 7 >>
An exhaust gas purification catalyst device obtained in the same manner as in Comparative Example 2 is placed on the upstream side of the exhaust gas flow.
An exhaust gas purification catalyst device obtained in the same manner as in Comparative Example 1 is placed on the downstream side of the exhaust gas flow.
They were arranged and connected in series to form a tandem type exhaust gas purification catalyst system. The SCR performance of the obtained exhaust gas purification catalyst system was evaluated in the same manner as in Example 1. The results are shown in Table 6.

Example 3 relates to an example of the catalyst device of the present invention having a single catalyst coat layer in which Cu-CHA type zeolite particles and iron-supported metal oxide particles are mixed. In the catalyst coat layer in the catalyst device of Example 3, Cu-CHA type zeolite particles and iron-supported metal oxide particles are mixed in the same catalyst coat layer, and it is considered that the contact frequency between the two is high. .. In Example 3, _{N 2} O slip amount is very small.

Comparative Examples 4 and 5 relate to a catalyst apparatus having a two-layered catalyst coat layer in which a layer containing Cu-CHA type zeolite particles and a layer containing iron-supported metal oxide particles are laminated, respectively. In the catalyst coat layer of these comparative examples, the Cu-CHA type zeolite particles and the iron-supported metal oxide particles are in contact with each other only at the contact interface of both layers. In Comparative Examples 4 and 5, compared to Example 3, N 2 _O slip amount of suppression is insufficient.

Comparative Examples 6 and 7 are tandem type in which a catalyst device having a catalyst coat layer containing Cu-CHA type zeolite particles and a catalyst device having a catalyst coat layer containing iron-supported metal oxide particles are connected in series. Regarding the catalytic system of. In the catalyst coat layer of these comparative examples, the Cu-CHA type zeolite particles and the iron-supported metal oxide particles are not in contact with each other. In Comparative Examples 6 and 7, as compared with Comparative Examples 4 and 5, N 2 _O slip amount was more often.

As described above, the effect of suppressing N 2 _O slip amount is found to Comparative Examples 6 and 7 of the tandem type, Comparative Examples 4 and 5 of the two-layer structure, in the order of a third embodiment of a single-layer structure, it continues to improve rice field. Therefore, from the viewpoint of suppressing N 2 _O slip amount, and the Cu-CHA-type zeolite particles and iron supported metal oxide particles are arranged in the same catalyst layer, it is possible to increase the contact frequency between the two It turned out to be desirable.

<< Analysis Example 1 >>
The spray-dried iron alumina particles used in Example 3 above were crushed and XRD was measured. _{As a result, no peaks derived from Fe 2} O ₃ crystals were observed near 2θ = 31 ° and 51 °, and _{it was confirmed that Fe 2} O ₃ was supported on alumina with extremely high dispersion. ..

The XRD measurement conditions were as follows.
XRD measuring device: Powder / thin film X-ray diffractometer manufactured by Rigaku Co., Ltd., model name "RINT TTR III"
Measurement method: Step scanning method Feed rate: 4 ° / min Diffraction angle range: 2θ = 5 to 85 °
Step width: 0.02 °
Acceleration voltage: 40kV
Acceleration current: 250mA

<< Analysis Example 2 >>
The impregnated iron alumina used in Example 5 above was pulverized, and XRD was measured in the same manner as in Analysis Example 1. _{As a result, peaks attributed to Fe 2} O ₃ crystals were observed near 2θ = 31 ° and 51 °, respectively, _{and Fe 2} O ₃ aggregated on alumina to form a crystal phase. Do you get it. The peak near 2θ = 31 ° is a shoulder peak.

The XRD charts obtained in Analysis Example 1 are shown in FIGS. 1 to 3, and the XRD charts obtained in Analysis Example 2 are shown in FIGS. 4 to 6, respectively. 1 and 4 are wide-area views of 2θ = 10 ° to 80 °, respectively, and FIGS. 2 and 4 are enlarged views of the range of 2θ = 29 ° to 35 °, respectively, and FIGS. 3 and 4 are shown. 6 is an enlarged view in the range of 48 ° to 54 °, respectively.

In FIGS. 4 to 6 relating to Analytical Example 2, an arrow is attached to the peak attributed to the _{Fe 2} O _{3 crystal.}

In these SRD charts, the peaks observed near 2θ = 20 °, 33 °, 37 °, 39.5 °, 46 °, 60 °, and 67 ° are all attributed to γ-alumina crystals. It is thought that.

Claims

An exhaust gas purification catalyst device including a base material and one or more catalyst layers on the base material.
At least one catalyst layer among the one or a plurality of catalyst layers is
It contains both Cu-CHA-type zeolite particles and iron-supported metal oxide particles in which iron is supported on the metal oxide particles.
Exhaust gas purification catalyst device.
Claimed that the metal oxide particles are oxide particles of one kind of metal selected from the group consisting of alumina, silica, titania, zirconia, and ceria, or composite oxide particles of two or more kinds of metals. The exhaust gas purification catalyst device according to 1.
The exhaust gas purification catalyst device according to claim 2, wherein the metal oxide particles are alumina particles.
Claimed that the amount of iron in the exhaust gas purification catalyst device is 0.3 g / L or more and 1.3 g / L or less as the mass of iron in terms of ferric oxide (Fe 2 O 3) per 1 L of the base material. The exhaust gas purification catalyst device according to any one of Items 1 to 3.
Claimed that the amount of iron in the exhaust gas purification catalyst device is 0.6 g / L or more and 1.3 g / L or less as the mass of iron in terms of ferric oxide (Fe 2 O 3) per 1 L of the base material. The exhaust gas purification catalyst device according to any one of Items 1 to 3.
The ratio of the Cu-CHA type zeolite particles and the iron-supported metal oxide particles in the catalyst layer is 5% by mass or more and 20% by mass or less as the mass percentage of the iron-supporting metal oxide particles to the total of both. The exhaust gas purification catalyst device according to any one of claims 1 to 5.
The exhaust gas purification catalyst device according to any one of claims 1 to 6, which is for selective contact reduction.
The method for manufacturing an exhaust gas purification catalyst device according to any one of claims 1 to 7.
(1) The Cu-CHA type zeolite particles and the iron-supported metal oxide particles are mixed and wet-ground to obtain a slurry for forming a catalyst layer, and (2) the catalyst is placed on the substrate. A layer-forming slurry is applied and fired to form the catalyst layer on the substrate.
Manufacturing method of exhaust gas purification catalyst device.
An exhaust gas purification method for purifying exhaust gas using the exhaust gas purification catalyst device according to claim 7.
The exhaust gas purification catalyst device is supplied with an exhaust gas and a reducing agent to reduce NO x in the exhaust gas to N 2 .
Exhaust gas purification method.